Kevin Kavanagh testified that he had no recollection of his encounter with Officer Anthony Federico

MINEOLA — A key witness took the stand at the trial of Rockville Centre Police Officer Anthony Federico who's accused of using excessive force in a May 2016 incident outside a bar.

Kevin Kavanagh testified Monday, saying his encounter with Officer Federico caused him to sustain a gruesome head injury. It happened after a fight between him and his brother Brendan Kavanagh and a group of young men. It became physical and Kevin says the last thing he remembers is getting flipped. Officer Federico came on the scene in response to that incident and then wound up in an altercation himself with the Kavanagh brothers.

Key evidence in the case is cell phone video of part of the altercation with the Kavanagh brothers and Officer Federico. During his testimony, Kavanagh said that he had no recollection of the incident with Federico, but remembers being flipped and waking up in the back of a police vehicle, bleeding and handcuffed yelling for help. The altercation at the center of this case is an alleged blank spot for Kavanagh. What he says he does remember is drinking beers and shots and using cocaine in the bathroom of a bar.

The prosecution argues excessive force was used and that at one point Federico using his Taser to allegedly pummel Kavanagh. But the defense says Federico was alone and dealing with a hostile crowd.

Initially, the Kavanagh brothers were charged in connection with this incident-but charges against them have since been dismissed.

One of the next witnesses is expected to be Brendan Kavanagh, Kevin's brother.